1. Field of the Invention
The present invention relates to a electronic controller unit having a flexible circuit board in which a connector forms a wall of the unit housing and to a method of manufacturing the electronic controller unit that does not require bending of a rigid plate to which the flexible circuit board is mounted.
2. Description of the Related Art
Sealed electronic controller units having an enclosed flexible circuit board are known as shown by U.S. Pat. Nos. 5,159,751 and 5,434,362. The flexible circuit board is mounted to a rigid aluminum plate that is subsequently bent to form the housing of the unit. As shown in U.S. Pat. No. 5,434,362 the aluminum plate is bent along numerous lines to form the six sides of the unit housing. In U.S. Pat. No. 5,159,751, the aluminum plate is bent with a single large radius bend to form three sides of the housing while a three sided enclosure portion 29 forms the remaining sides of the housing. The connectors 24 and 25 are electrically connected to the flexible circuit and are sealed to the enclosure portion 29. As explained in the above-mentioned patents, care must be taken in bending the aluminum plate to avoid damage to the circuit board and the electrical components mounted thereon.
The present invention seeks to overcome the difficulties in bending the plate carrying the circuit board by a novel structure of the electronic controller unit that eliminates the bending of the plate and a unique method of manufacturing the electronic controller unit.
The electronic controller unit of the present invention includes first and second base plates that during the initial steps of the manufacturing process are held in a fixed position relative to one another in which they are coplanar and spaced apart. Typically, the base plates are made of aluminum and are held in place by an integral frame consisting of a pair of side rails. A flexible circuit is bonded to one side of the base plates and has an intermediate portion that spans between the two base plates. The electrical components are mounted on the flexible circuit and are electrically connected thereto. A connector is placed on the opposite side of the flexible circuit from the electrical components, between the two base plates, and is also electrically connected to the flexible circuit.
The integral side rails holding the base plates in place are subsequently removed, allowing the two base plates to be moved relative to one another. The circuit is flexed in two locations, one on each side of the connector, as the two base plates are moved to a spaced, parallel relationship to one another. The connector is subsequently sealed to the base plates along one edge of the each base plate with the connector forming one wall of the unit housing while the base plates form opposite major faces of the unit housing. A frame forms the remaining three sides of the unit housing between the two base plates and is also sealed to the base plates and to the connector. The unit housing thus utilizes the connector as one wall thereof. Since the unit is manufactured with the flexible circuit bonded to two separate base plates, there is no need to bend an aluminum plate or other rigid material.